Herein disclosed are carrier and developer compositions thereof, and more specifically the carrier comprises magnetite having, in embodiments, a specific diameter, and the carrier has a specific conductivity and carrier breakdown voltage. Also, in embodiments, a developer is included. The carriers and developer compositions described herein are useful in a number of known electrostatographic imaging and printing systems, especially in magnetic image character recognition processes (MICR).
Existing developer tested in a MICR machine exhibited poor MICR characteristics, including poor print characteristics. In addition, known developers have been shown to exhibit poor tribo and At stability. Moreover, known developer have shown unacceptable developer life. In addition, known carriers and developers have demonstrated unacceptable conductivity.
U.S. Pat. No. 6,764,799 discloses carrier conductivities of from about 1031 2 to about 10−15, or from about 10−11 to about 10−13 S/cm.
U.S. Pat. No. 4,513,074 discloses developer compositions having carrier conductivities of from about 10−9 to about 10−12 ohm-cm−1.
U.S. Pat. No. 5,518,855 discloses carrier conductivity of from about 10−17 to about 10−6, or 10−14 to about 10−6 (ohms-cm)−1. 
U.S. Pat. No. 5,567,562 discloses carrier conductivity of from about 10−6 to about 10−14 (ohms-cm)−1.
U.S. Pat. No. 5,567,562 discloses carrier conductivity of from about 10−6 to about 10−15, from about 10−9 to about 10−15, and developer conductivities of from about 10−6 to about 10−15 (ohms-cm)−1.
U.S. Pat. No. 5,700,615 discloses carrier conductivity of from about 10−9 to about 10−17.
U.S. Pat. No. 5,744,275 discloses carrier conductivity of from about 10−9 to about 10−17.
U.S. Pat. No. 5,945,244 discloses developer conductivity of from about 10−6 to about 10−17, from about 10−10 to about 10−6, and from about 10−8 to about 10−6 (ohms-cm)−1.
U.S. Pat. No. 5,968,703 discloses developer conductivity of from about 10−12 to about 10−7 (ohms-cm)−1 and carrier conductivity of about 10−10, or less than 10−14 (ohms-cm)−1.
U.S. Pat. No. 6,051,354 discloses carrier conductivity of from about 10−10 to about 10−7, from about 10−6 to about 10−17, and about 10−6 to about 10−8.
U.S. Pat. No. 5,482,805 teaches a toner consisting essentially of resin particles, magnetite pigment, carbon black pigment, rhodamine charge additive, wax, and a surface mixture of aluminum oxide, strontium titanate and polyvinylidene fluoride; and wherein said resin particles are present in an amount of from about 50 to about 90 weight percent, said magnetite is present in an amount of from about 25 to about 40 percent, said carbon black is present in an amount of from about 1 to about 5 weight percent, said wax is present in an amount of from about 3 to about 15 weight percent, and said aluminum oxide, strontium titanate and polyvinylidene fluoride are each present in an amount of from about 0.5 to about 2 weight percent.
U.S. Pat. No. 5,486,443 discloses the toner of 5,482,805, except that aluminum oxide is replaced with silica.
Therefore, there is a need for carriers and developers that exhibit superior MICR characteristics, including improved print characteristics. In addition, there is a need for carriers and developers, which will exhibit improved tribo and At stability. Moreover, there is a need for a carrier and developer having superior developer life. In addition, there is a need for toners that provide acceptable MICR characteristics.